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Card Compass and mount


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On 12/17/2016 at 12:00 PM, carusoam said:

No matter which magnetic compass you use... ANDS is still going to be part of the math...

The vertical compass is an ordinary magnetic compass with a gear driven vertical card...

My 65C had huge interference problems caused by the magnetic shadow of the center tube.  The balancing balls would be a probable solution for that as well...

Later planes got a SS tube in that location...

The nice part about the vertical card is the direction of the card matches the direction of the turn.  This makes the ANDS a bit easier to deal with...

PP thoughts, only.  I could be completely out to lunch on this...

Best regards,

-a-

I'm considering adding a vertical compass card to my '76 F.  When I mentioned it to the avionics guy on my field, he discouraged it because of the hassle with the  tubular airframe and magnetism.  Does he have a good point?

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9 minutes ago, apenney said:

I'm considering adding a vertical compass card to my '76 F.  When I mentioned it to the avionics guy on my field, he discouraged it because of the hassle with the  tubular airframe and magnetism.  Does he have a good point?

I've had the same conversation with my avionics shop. That was all I needed to hear... the only thing I use my current whiskey compass for is as a place to hang the co-pilot's headset when the plane is parked.

I do recall degaussing my old M20E 40 years ago in order to be able to get the compass to swing reasonably close. But in those days of DGs subject to precession the compass served a real purpose. 

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I'm considering adding a vertical compass card to my '76 F.  When I mentioned it to the avionics guy on my field, he discouraged it because of the hassle with the  tubular airframe and magnetism.  Does he have a good point?

 

What your avionics guy said is true for any magnetic compass in a Mooney. The tubular structure is subject to magnetism. The usual cause is power lines draped over the structure both temporarily (using an electric vacuum cleaner) or permanent (power lines to avionics run along the structure).

 

The nice thing about the PAI-700 type of compass is that you can apply balancing balls on it which can help offset some of the acquired magnetism.

 

Bob doesn’t worry about a magnetic compass because he has a magnetometer in the plane. Like Bob, with multiple magnetometers in my plane, a working mechanical compass is less of a worry, but I do keep mine calibrated.

 

Someone on MooneySpace recently posted the calibration procedure for the vertical compass. Not that difficult. Where it gets difficult is if you have a significant magnetism issue and you need to degauss the plane. I think DXB did this in his.

 

 

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I priced out a vertical compass with bracket and labor and I determined the $500+ was better spent toward the Aspen E5 or Garmin G5 fund as they have a separate magnetometer. Until then, I’m going to let the hanger elves keep the whiskey compass on life support.


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I found a precision on ebay for half the original new cost.   I learned they are made in Houston.  Figured a tune up should not be that big of a hassle.  It's one of those things. You don't invoke passenger confidence with a half filled compass bouncing around.

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4 minutes ago, Yetti said:

I found a precision on ebay for half the original new cost.   I learned they are made in Houston.  Figured a tune up should not be that big of a hassle.  It's one of those things. You don't invoke passenger confidence with a half filled compass bouncing around.

You have passengers who would even notice? I'm impressed! :)

Edited by midlifeflyer
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I had a card compass in my Cessna when I bought it some ten years ago and grew to love it.  When I got my C I immediately upgraded to one using the PAI Mount specifically for the Mooney.  The compass is great, but the $50+ dollar Mount broke from constant flexing on an aluminum bend, work hardening and breaking.  I ordered another Mount and will brace the bottom to prevent the vibration induced failure.  Keep this in mind when you mount your compass.

The card compass does indeed have lead and lag in just about the same number of degrees as a whisky compass.  An instrument pilot should understand the lead and lag and even practice rolling out with it in mind.  If the time ever comes that while in the clouds all your fancy dials and glass fail, you will be glad you did.

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On 3/24/2019 at 12:31 AM, apenney said:

I'm considering adding a vertical compass card to my '76 F.  When I mentioned it to the avionics guy on my field, he discouraged it because of the hassle with the  tubular airframe and magnetism.  Does he have a good point?

I had a Precision vertical compass card installed in my '76F at the last annual. It's been great. Very happy with it.

They have changed the design a little from what is shown on their website. They now have a 'Made in USA' detail printed on the face. Nothing against being patriotic, but I'd rather they hadn't put it there.....

DSC02761.JPG

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On 3/23/2019 at 11:51 AM, gsxrpilot said:

I'd love to take the card compass off the center bar. And with so many magnetometer you'd think it could be eliminated. :(

I'd think so too. VFR instrument requirements only state a "magnetic direction indicator" is needed.  They do not specifically say compass.  Magnetometer would seem to suffice.  IFR instrument requirements do not make any additional requirement for a compass.  I ended up replacing my compass and going through a whole degaussing nightmare because the IR practical test standards do make reference to testing compass turns under partial panel.  Of course, I did not have to do compass turns after all that effort to get the compass fixed.  If someone can definitively tell me that the regs do not require a compass, I will happily put my nice year old SIRS compass on sale at Mooneyspace.

 

 

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I read some old posts here about deguassing and it seems quite intensive. Is there a machine that can be rented to do this or does one have to build one like MacGyver? And after the contraption is built, how do you use it? Like where do you aim it?

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1 hour ago, tigers2007 said:

I read some old posts here about deguassing and it seems quite intensive. Is there a machine that can be rented to do this or does one have to build one like MacGyver? And after the contraption is built, how do you use it? Like where do you aim it?

You can buy ones like this if you don't want to pull out of an old TV:

https://www.verical.com/pd/gc-electronics-hand-tools---accessories-9317-1037549?gclid=EAIaIQobChMI45HRuo6c4QIVU-DICh1ESwn0EAYYASABEgK_ovD_BwE

You may want to put a heating element like this in series with it to bump up the current:https://www.lightbulbdepot.com/products/details/di/660w-120-volt-cone-heater-heat-element-not-bulb/29036a/

This is a two man job, be careful not to burn or electrocute yourself or make the problem worse - the coil must be turned on and off OUTSIDE the plane.  

Mooney describes using a growler.  Their procedure is in this service bulletin: 

https://cdn2.hubspot.net/hubfs/4147179/technical_documents/service_bulletins/sbm20-150a.pdf?t=1525208387815

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3 hours ago, Sime said:

I had a Precision vertical compass card installed in my '76F at the last annual. It's been great. Very happy with it.

They have changed the design a little from what is shown on their website. They now have a 'Made in USA' detail printed on the face. Nothing against being patriotic, but I'd rather they hadn't put it there.....

DSC02761.JPG

Did you have any issues regarding magnetism of the tubular frame requiring balancing balls or degaussing? 

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3 hours ago, DXB said:

I'd think so too. VFR instrument requirements only state a "magnetic direction indicator" is needed.  They do not specifically say compass.  Magnetometer would seem to suffice.  IFR instrument requirements do not make any additional requirement for a compass.  I ended up replacing my compass and going through a whole degaussing nightmare because the IR practical test standards do make reference to testing compass turns under partial panel.  Of course, I did not have to do compass turns after all that effort to get the compass fixed.  If someone can definitively tell me that the regs do not require a compass, I will happily put my nice year old SIRS compass on sale at Mooneyspace.

Hmmm... now you got me thinking...

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13 minutes ago, tigers2007 said:

This seems like some sort of black magic ritual. I’d love to see a video or photos of MS’rs doing this.


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When you do it, it looks rather like a black magic ritual.   

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21 minutes ago, apenney said:

Did you have any issues regarding magnetism of the tubular frame requiring balancing balls or degaussing? 

No, no issues at all. The compass is accurate in all directions. No balancing balls required. Also, my new compass sits a little higher up so it's further away from the panel compared to some others I have seen...that may help.

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One thing I have always noticed with my PAI-700, during takeoffs, it always does ANDS backwards. Wonder if anyone else ever saw this. Runway heading is 04. Once the gear is stowed, it returns to 04. Another oddity to explain.




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9 hours ago, gsxrpilot said:

Hmmm... now you got me thinking...

Uh oh!  Paul is thinking.:D

Seriously though, what can be considered a MAGNETIC direction finder other than a compass, either conventional or remote.  I’m anxious to read what you come up with.

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One advantage (albeit extremely rare) to an old whiskey compass is if in imc and you loose EVERYTHING, you can head south and the leading response to a turn will be exaggerated, theoretically enabling you to keep wings level. Don't know if a card compass is similar?

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